Non-pneumatic survivable tire mounting system for conventional wheels

ABSTRACT

A non-pneumatic tire and wheel assembly incorporates a tire tread and a conventional vehicle wheel with an elastomer tire body element and integral wall elements extending radially inward from the tire body element for sealing engagement with the wheel. The tire body element includes multiple concentric layers with alternating spokes. A bonded multilayer cover may be employed which is received within a recess in an outer surface of the tire body element from the tire tread. An attachment plate is engaged to the cover and attached to the wheel.

REFERENCE TO RELATED APPLICATIONS

This application is co-pending with U.S. patent application Ser. No.______ entitled NON-PNEUMATIC SURVIVABLE TIRE, COVER AND FABRICATIONPROCESSES by Daniel J Perron, Eldon C. Rogers, Darrell M. Storvick,Timothy L. Williams, Dennis Yee and D'Arcy R. Chadwick, attorney docketno. 10-0149, filed substantially concurrently herewith the disclosure ofwhich is incorporated herein by reference as though fully set forth.

BACKGROUND INFORMATION

1. Field

Embodiments of the disclosure relate generally to the field ofnon-pneumatic tires and more particularly to embodiments for asurvivable non-pneumatic tire having molded construction with a flexiblespoke structure for tactical wheeled vehicle application with anintegral pneumatic interface for mounting to conventional wheels

2. Background

Tactical military vehicles are subject to extreme environments and thepotential for combat damage. Existing pneumatic tires in use on manyvehicles may be vulnerable to blast and fragmentation effects fromimprovised explosive devices (IED) and other explosive or penetratingthreats which render military vehicles inoperable and can leave theircrew stranded in harms way. Additionally, flexing of tire walls inpneumatic tires may create heating that may increase detectable thermalemissions. Armor shielding provides protection from small arms fire andfragments, but greatly increases vehicle weight, reduces payload,reduces mobility and maneuverability, and reduces vehicle range.Existing wheel/tire covers are mounted outboard of the pneumatic tiredue to the tire wall bulge where they are vulnerable to terrainobstacles and may be damaged or destroyed in the course of ruggedterrain operations.

Non-pneumatic tires have been introduced for improved durability andpuncture resistance on vehicles for many applications including tacticalmilitary vehicles for the ability to withstand blast effects andprojectile punctures that could disable a vehicle with pneumatic tires.Solid rubber tires provide desired puncture resistance but may be heavyand have excessive rotating inertia for many desired applications.Wheel/tire combinations created from plastic or composite matrixmaterials are entering use but may be difficult to fabricate in a mannerto be interchangeable with existing pneumatic tire and wheel systems onvehicles.

Pneumatic tires allow mounting to a range of conventional wheel for useon various vehicles using well established tools and mounting machines.Additionally, such capability allows easy replacement of tires that dobecome damaged or reach end of life wear. Non-pneumatic tire systems arenot currently mountable to convention vehicle wheels.

It is therefore desirable to provide non-pneumatic tire/wheelcombinations which exhibit the desired survivability capabilities. It isalso desirable to provide non-pneumatic tire/wheel combinations that aremountable to existing convention wheels for pneumatic tire/wheelsystems.

SUMMARY

Embodiments disclosed herein provide a non-pneumatic tire and wheelassembly incorporating a tire tread and a conventional vehicle wheelwith a molded elastomer tire body element received in the tread andhaving integral wall elements extending radially inward from the tirebody element for sealing engagement with the wheel. The tire bodyelement includes multiple concentric layers with alternating spokes.

In certain embodiments the molded elastomer tire body element has anouter surface recessed from the tire tread and further incorporates abonded multilayer cover received within the recess. An attachment plateis bonded to the cover and attached to the wheel.

Fabrication of an enhanced survivability tire assembly of theembodiments disclosed is accomplished by forming inner and outer moldelements with strut and aperture dimensions adapted for the desiredspoke design and mating rubber cast blocks. A center plug is formed andreleasably carried chamber forms are attached thereto. A tread is thenprepared for casting and the tread, outer mold element, center plug withchamber forms, inner mold element and rubber casting blocks areassembled. An elastomer is then introduced into the mold assemblythrough fill tubes inserted in fill apertures in the center plug andchamber forms to cast concentric layers with spokes around the rubbercast blocks and integral side walls around the chamber forms. Theelastomer is then allowed to dry. The rubber blocks and mold elementsare then disassembled from the tire assembly which is cured at hightemperature. The tire assembly is then mounted on a conventional wheelwith conventional mounting tools to deform the integral side walls. Apneumatic chamber formed by the side walls is then inflated.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments of the present disclosureor may be combined in yet other embodiments further details of which canbe seen with reference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an embodiment of the non-pneumatic tire andwheel assembly with cover;

FIG. 2 is a front section view of the embodiment of FIG. 1;

FIG. 3 is an isometric exploded view of the elements of the embodimentof FIG. 1;

FIG. 4 is an exploded view of the tooling for fabrication of theembodiments described; and,

FIG. 5 is a flow chart depicting the fabrication and mounting of theembodiment of FIG. 1.

DETAILED DESCRIPTION

The embodiments described herein with respect to tactical vehicle useprovide a non-pneumatic tire element with hollow spokes that do notblock blast pressure, instead allowing the pressure wave to pass-throughthe tire venting the pressure and reducing likelihood of the tire beingblown off the wheel during a blast event. The exemplary urethane casttire is resistant to small arms fire and is not compromised from minorsmall arms bullet impacts. The urethane spokes are durable and ofsufficient number and strength to provide redundant functionality evenafter punctures from bullets, nails or other small projectiles.Concentric spoke layers allow a greater number of load paths andflexibility. These redundant load paths provide greater tolerance to IEDblast protection and small arms fire. “Run flat or damaged” capabilityis inherent by eliminating the need for the tire to contain pressurizedair.

The embodiments additionally include a pneumatic interface between thetire element and wheel created by integrally molded sidewalls extendingover an inner portion of the tire radial extent which engage standardmounting beads on conventional wheel rims and are inflatable to engagethe wheel in a conventional manner. This allows the complete structureof the embodiment to be mounted to any Original Equipment Manufacturer(OEM) wheel using standard tire mounting equipment. Additionally, thispneumatic interface allows the driver in an appropriately equippedtactical vehicle to adjust air pressure and ride smoothness/tractionwhile in motion using the existing Central Tire Inflation (CTI) systemas in a conventional pneumatic tire/wheel system.

The embodiments further may incorporate a cover that mounts inset to thewheel tread providing high durability since the cover does not protrudebeyond the outer profile of the tire tread reducing exposure topotentially damaging debris such as rocks and sticks during operations.Convex shape of the cover and durable material returns to original formafter buckling during compression of the tire/wheel in operation. Thecover keeps the tire spokes from filling with mud and dirt therebymaintaining wheel balance and ride smoothness. The combination of theelements in the embodiments reduces heat emissions associated withpneumatic tires by eliminating the rubber sidewalls found on pneumatictires and masking the tire/wheel with the wheel cover. Armor may beincluded in the cover for the pneumatic interface portion of theembodiment. The limited radial extent of the pneumatic interface reducesthe size and weight of such armor significantly over any conventionalpneumatic tire armor.

The fabrication process for the disclosed embodiments allows for ease ofmanufacture of the wheel/tire combination and design parameters such asspoke thickness/reinforcing fibers can easily be varied to match vehicleload requirements and ride flexibility. Further, the tire/wheel asfabricated may then be mounted on OEM rims and therefore can be builtfor any wheeled vehicle, including tactical vehicles such as HMMWV orStryker providing design and manufacturing cost savings.

Referring to FIGS. 1, 2 and 3, the embodiment shown provides anon-pneumatic tire and wheel assembly 8 which incorporates a moldedelastomer tire body element 10 having concentric layers 12 and 14 withalternating spokes 16 of elastomer web. For the exemplary embodimentsdisclosed herein, urethane is employed as the elastomer. Howeverdepending on specific application requirements for the vehicle tiresimilar materials with durometers ranging from approximately 40 to 90 onthe Shore A scale may be employed. The tire body element 10 is engagedat an outer circumference 21 by a tread 22 of vulcanized rubber orsimilar material having a traction lug and groove pattern comparable toconventional pneumatic tires. The tread may be similar in design andconstruction to a tread blank employed in retreading of conventionalpneumatic tires. Integral wall elements 17, 18 extend radially inwardfrom the tire body element 10 and include outer and inner engagementbeads 19, 20 on an inner circumference to engage a conventional tire rim24 of a conventional vehicle wheel 26 which may be constructed inconventional fashion with forged, pressed or cast steel or aluminumstructure. For the embodiment shown in the drawings, two concentriclayers of spokes are shown for the non-pneumatic tire body elements witha radial length comparable to one layer for the integral wall elements.The number of concentric layers and the relative radial length of theintegral wall elements may vary for alternative embodiments wherein asufficient resilient bight length is maintained in the integral wallelements for mounting over a conventional wheel rim.

An outer circumferential engagement dome 32 is present on the outercircumference of the tire body element 10 which engages a matingdepression in the inner wall 34 of the tread to enhance engagement ofthe tire body element to the tread to prevent separation duringoperation. In alternative embodiments additional adherence features maybe employed in tread for additional engagement of the molded tire bodyelement or the tread may be integrally molded with the tire bodyelement.

As best seen in FIG. 2, the wheel incorporates a web 36 extending fromrim 24 for standard engagement of a vehicle axle hub 38. The web mayinclude ventilating perforations 40 for brake cooling or wheel weightreduction and includes standard lug bores 42 for attachment of the wheelto the hub. Inner bead ring 44 and outer bead ring 45 terminate the rimprofile. Engagement beads 19, 20 on the integral wall elements 17, 18are received by the bead rings 44 and 45 in a manner comparable to aconventional tire allowing pneumatic inflation of chamber 46 created bythe integral wall elements, an inner circumferential surface 47 of thetire body element 10 and the wheel rim 24 effectively forming apneumatic bladder. In alternative embodiments an inner tube 48 (shown inphantom in FIG. 2) may be employed for enhanced pneumatic sealing of thebladder.

A relief 49 associated with the outer bead ring receives a mounting ring50. A cover 52 is received on an outer surface 54 of the tire bodyelement and attached to mounting ring 50 with fasteners 51. The outersurface is inset from the tread side wall 56 placing the cover in aprotected relief in the tread and tire body element 10 to reduceexposure to potentially damaging debris such as rocks and sticks duringoperations. The cover reduces mud and dirt introduction into the tirebody element spokes 16 from the exterior of the mounted wheel therebymaintaining wheel balance and ride smoothness. Cover 52 is convex withrespect to outer surface 54 thereby providing resiliency to return tooriginal form after buckling during compression of the tire/wheel inoperation. The cover is a multilayered concentric composite structure.Attachment plate 50 is bonded to cover 52 for attachment to the wheel.In alternative embodiments, a ring of armor 53 may be embedded in thecover for protection of the pneumatic portion created by the integralwall elements extending from the tire body element. For the embodimentshown, fasteners 51 are quick release ball lock alignment pins extendingthrough the attachment plate and into the wheel rim.

For exemplary embodiments, the elastomeric material employed for thetire body element is urethane such as PR1664D two-part, castable 100%solids, polyurethane elastomer produced by PRC-DeSoto International,Inc., CDP Division, 2817 Empire Avenue, Burbank, Calif. 91504. Materialsfor alternative embodiments may include Two Component Polyurethane CastElastomer Systems such as Tadco S Series with Shore Hardness from A70 toA99 produced by T.A. Davies Company, 19500 S Alameda St., East RanchoDominguez Calif. (having Polyether (PTMEG) Polyol Mixture and Polyetheror Polyester/MDI Quasi-Prepolymer Isocyanate) and industrial tire rubbercompounds such as natural rubber, styrene butadiene rubber, andpolybutadiene rubber.

The resiliency of the tire body element 10 is determined based on theurethane composition and spoke design. Thickness of the web for thespokes in the exemplary embodiments ranges from approximately 1/16″ to½″ depending on specific application and may be varied in the adjacentconcentric layers of alternative embodiments for tailoring overallwheel/tire body element flexure during operation. For the exemplaryembodiment shown in the drawings, the radial spokes in the concentriclayers are 0.375″ and the concentric rings between the spokes are0.3125″. In the embodiment shown, the spokes 16 alternate forsymmetrical adjacent support of spokes in adjacent layers. Additionally,a simple rectangular or trapezoidal design is shown for the crosssection of the spokes. In alternative embodiments a profiled crosssection may be employed for performance enhancement. Hardness (orflexibility) of tire body element may be of constant durometerthroughout the concentric layers, or may vary by up to 50% to optimizeperformance for flexibility. The elastomer mix can be varied in realtime as the pour proceeds with material of differing durometers injectedin to the different spoke layers. For the exemplary embodiments, theintegral wall elements 17, 18 are approximately 2 inches in height orabout ¼ of the overall radial extent of the total tire body element 10extending from the wheel rim. The wall thickness in the exemplaryembodiment varies from approximately 0.25″ at the innermost edge (thetire bead) to approximately 0.125″ for most of the 2″ wall height, andback to 0.25″ at the outermost corner of the wall where it transitionsto the spokes. Wall height and flexibility are determined to accommodatenecessary resiliency for expansion over the wheel rim during mounting orremoval while limiting the overall height of the wall to minimize thedepth of the pneumatic portion of the tire element and thereby the areapresented for potential damage by projectiles or blast and to enhancethe run flat/damaged capability of the non-pneumatic tire system as awhole.

The spoke design provides a net open area of 61% to 78% of the totalsurface of the tire body element depending on the number of concentriclayers retained and the radial extent of the required bladder wallthereby reducing the likelihood of penetration of the tire body elementby projectiles such as small arms fire and maximizing the blow throughopen area for blast survivability. The alternating symmetrical adjacentsupport allows fracture or destruction of a number of spokes in thewheel without a disabling performance reduction in the wheel/tire bodyelement system.

The combination of the tire body element 10 and cover 52 in theembodiments shown reduces heat emissions associated with pneumatic tiresby eliminating the rubber sidewalls found on pneumatic tires and bymasking the tire body element 10 and wheel 26 with the wheel cover.

Fabrication of the non-pneumatic tire assembly of the exemplaryembodiments is accomplished by casting with a pour molding process. Asshown in FIG. 4, an outer mold element 70 is received within the tread22. In various embodiments, outer mold element 70 may extend from a flatplate 72 with the thickness of the outer mold element corresponding tothe recess depth of the tire body element outer surface 54 from thetread outer wall 56 or have an outer rim for engagement of the treadouter wall 56 for accurate depth placement within the tread to createthe recess of the tire body element outer surface 54. The outer moldelement incorporates struts 74 corresponding to the spoke locations inthe tire body element with apertures 76 to receive rubber mold blocks aswill be described in greater detail subsequently. A center plug 78 iscentered on the outer mold element. Pneumatic chamber forms 79 arereleasably carried by the center plug to form the pneumatic chamberwithin the integral walls of the tire assembly.

An inner mold element 80 is concentrically received over tread 22. Theinner mold element incorporates struts 82 and apertures 84 symmetricalwith the outer mold element. Molding material fill tube 86 interfaceswith apertures 88 and 89 in the center plug and pneumatic chamber forms.For the embodiment shown, three mating apertures through the pneumaticchamber forms from a central fill tube are employed.

Rubber casting blocks 90 are inserted through apertures 84 in the innermold element 80 to be received in the corresponding apertures in theouter mold element 70 to complete the casting mold. Sizing of the strutsand apertures in the outer and inner mold elements and the rubbercasting blocks provides corresponding sizing of the spokes in the tirebody element as cast. The chamber forms determine the configuration andsizing of the pneumatic chamber and the associated integral walls of thetire assembly. For casting, the elastomeric is introduced through thefill tubes to completely fill the interstitial spaces between the rubbermold blocks.

The cast non-pneumatic tire assembly is then allowed to dry at roomtemperature. The rubber mold blocks and outer and inner mold elementsare then removed. The chamber forms are released form the center plugand the plug is removed. The chamber forms may then be collapsed out ofthe chamber for removal. The cast non-pneumatic tire and wheel assemblyis then cured at high temperature

For the exemplary PR1664D Urethane material, high temperature cure maybe accomplished in 3 hours at 212° F. or 12 hours at 180° F. or 16 hoursat 160° F.

While disclosed for the embodiments herein as a pour casting process, inalternative fabrication methods injection molding of the tire bodyelement in standard split molds may be accomplished with bonding of thetread to the tire body element after cure. In other alternativeembodiments, the tread may be cast in conjunction with the tire bodyelement using tooling for pressure injection molding.

FIG. 5 demonstrates the manufacturing process for the cast non-pneumatictire with pneumatic bladder and wheel assembly as described. In step 500the inner and outer mold elements are machined or cast from aluminum orother appropriate tooling material with strut and aperture dimensionsadapted for the desired spoke design and integral wall heightestablished to achieve required structural properties for service use.Mating rubber cast blocks are prepared for insertion into the aperturesin the inner and outer mold elements. The tread is then prepared forcasting, step 502. Tread from a conventional off the shelf (COTS) tiretread such as that employed for convention tire retreading may beemployed. The tread, outer mold element, center plug with chamber forms,inner mold element and rubber casting blocks are then assembled formolding, step 506. The outer mold element is received within the tiretread to create a recess for protective mounting of a cover as describedsubsequently. Mounting of the outer mold element on a tooling plateallows the tire tread to be supported by the tooling plate with theouter mold inserted. The elastomer, urethane for the exemplaryembodiment as previously described, is then introduced into the moldassembly through the fill tubes, step 508. The elastomer is allowed todry, step 510, and the tooling is then disassembled from thenon-pneumatic tire assembly 512. A high temperature cure is thenaccomplished for the non-pneumatic tire assembly, step 514, providing acompleted system. The tire assembly is then mounted on a conventionalwheel using convention mounting equipment and tools, step 516, and thepneumatic bladder is inflated, step 518. For protection of thenon-pneumatic and bladder elements of the tire, a cover may then bemounted to the wheel, step 520.

Having now described various embodiments of the disclosure in detail asrequired by the patent statutes, those skilled in the art will recognizemodifications and substitutions to the specific embodiments disclosedherein. Such modifications are within the scope and intent of thepresent disclosure as defined in the following claims.

What is claimed is:
 1. A non-pneumatic tire and wheel assemblycomprising: a tire tread; a conventional vehicle wheel; a moldedelastomer tire body element received in the tread and having a pluralityof concentric layers with alternating spokes; and, integral wallelements extending radially inward from the tire body element forsealing engagement with the wheel.
 2. The non-pneumatic tire and wheelassembly as defined in claim 1 wherein the elastomer tire body elementand integral wall elements are molded from urethane.
 3. Thenon-pneumatic tire and wheel assembly as defined in claim 1 wherein theelastomer tire body element and integral wall elements are molded froman elastomer with durometer ranging from approximately 40 to
 90. 4. Thenon-pneumatic tire and wheel assembly as defined in claim 1 wherein thewheel incorporates a rim with inner an outer bead rings and the integralwall elements include beads for sealing engagement on the bead rings toform a pneumatic chamber.
 5. The non-pneumatic tire and wheel assemblyas defined in claim 1 wherein an outer circumference of the tire bodyelement incorporates an outer circumferential engagement dome engaging amating depression in an inner wall of the tread.
 6. The non-pneumatictire and wheel assembly as defined in claim 1 wherein the moldedelastomer tire body element has an outer surface recessed from the tiretread and further comprising: a cover received within the recess; and,an attachment plate engaged to the cover and attached to the wheel. 7.The non-pneumatic tire and wheel assembly as defined in claim 6 whereinthe outer bead ring has a relief and said attachment plate is receivedwithin the relief.
 8. The non-pneumatic tire and wheel assembly asdefined in claim 4 further comprising an inner tube received within thechamber.
 9. A vehicle non-pneumatic tire and wheel assembly comprising:a vulcanized rubber tire tread having an outer sidewall; a steel wheelhaving a rim with inner and outer bead rings, said outer bead ringhaving a relief; a urethane tire body element molded within the treadand having an outer circumferential engagement dome engaging a matingdepression in an inner wall of the tread, and further having twoconcentric layers with spokes having varying web thickness forpredetermined resiliency and alternating for symmetrical adjacentsupport of spokes in adjacent layers, the layers having an outer surfacerecessed from the outer sidewall of the tread and integral wall elementsextending radially inward from the concentric layers, said integral wallelements terminating in inner and outer beads for engagement with theinner and outer bead rings of the wheel forming a pneumatic chamber; abonded multilayer cover received within the recess from the outersidewall of the tread; and, an attachment plate bonded to the cover andreceived within the relief of the outer bead, said ring attached to thewheel with releasable fasteners.
 10. A method for fabrication of anenhanced survivability tire assembly comprising: forming inner and outermold elements with strut and aperture dimensions adapted for the desiredspoke design and mating rubber cast blocks; forming a center plug andreleasably carried chamber forms; preparing a tread for casting;assembling the tread, outer mold element, center plug with chamberforms, wheel, inner mold element and rubber casting blocks; introducingan elastomer into the mold assembly through fill tubes inserted in fillapertures in the center plug and chamber forms to cast concentric layerswith spokes around the rubber cast blocks and integral side walls aroundthe chamber forms; allowing the elastomer to dry; disassembling therubber blocks and mold elements from the tire assembly; curing at hightemperature; mounting the tire assembly on a conventional wheel withconventional mounting tools to deform the integral side walls; and,inflating a pneumatic chamber formed by the side walls.
 11. The methodof claim 10 wherein the step of forming the inner and outer moldelements further comprises: concentrically receiving the inner and outermold elements with the tread, the outer mold intruding into the tread tocreate a recess of the tire body element outer surface.
 12. The methodof claim 11 further comprising mounting the outer mold element on atooling plate.
 13. The method of claim 11 further comprising mounting acover received within the recess.